My Geography teacher has started an experiment which involves me writing about what I have learnt in my lessons and about any geographical news that interests me. My Geography teacher is also going to write a blog about what she teaches me (and therefore what I should have learnt!) and hopefully the two blogs will match up. The idea is that this will not only help me to consolidate what I learn but that it will also help fellow students do the same and keep up to date with current issues.

Friday, 13 May 2011

Rejuvenation

After much request, I am going to write a short post purely on the idea of rejuvenation in rivers (to those of you who I said that I would do it on Wednesday/Thursday, I apologise but blogger hasn't been working properly over the last few days). So, better late than never, here goes........

What is rejuvenation?

Rejuvenation is the renewal of a rivers energy in response to a relative fall in base level. Base level is the same as current sea level and so a drop in base level can be caused by either eustatic sea level fall, isostatic rebound or tectonic activity. Due to the fact that all rivers try to reach the graded profile (a theorectical concept where all three river processes are in equilibrium and calibrated to current base level), a drop in base level usually provokes a restart of erosion, predominantly in the form of vertical erosion. Rejuvenation always starts at the mouth of a river and works its way towards the soure, therefore headward erosion is also active.

How does rejuvenation affect rivers?

The restart of erosion and reduction in deposition, provoked by a fall in base level, leads to the formation of landforms that would not normally be found in rivers.

INCISED MEANDERS:

There are two types of incised meanders, ingrown and entrenched and they can be found in areas like the Grand Canyon.

Ingrown meanders:
:- form when lateral erosion operates too (therefore indicates a more gradual drop in base level) and so the valley floor is deepened which means that the channel only occupies part of it.
:- they have an asymmetrical cross section

Entrenched meanders:
:- created, purely, by vertical erosion (their presense indicates a rapid fall in base level) and often form in hard rock areas.
:- they are deep cut and gorge like
they have a symmetrical cross section

KNICK POINTS:

Knick points appear on a rivers long profile and are, almost, like the steps down a river takes to reach the new base level. They relate to the extent to which a river has created a new profile in response to the new base level.

:- they can be identified by a break in slope and so are often marked by a waterfall
:- they reflect the process of headward erosion aswell as vertical erosion as the river has a renewed ability to erode vertically

:- Knick points often form waterfalls and, in areas where they form but there is no alteration in rock type, they clearly show rejuvenation has occured as waterfalls normally form due to differential erosion resulting in undercutting

RIVER TERRACES:

There are two types of river terraces, paired and unpaired, and they are the remains of the former floodplain which has been abandoned because the river has eroded too deeply for the floodplain to be accessed. London sits on river terraces and by looking at terraces it is possible to work out how many relative falls in base level have occured.

Paired:

:- they are on the same level on each side of the channel and so indicate rapid down cutting

Unpaired:

:- occur when the fall in base level is slower

:- the terraces will be present on different sides of the channel at different levels. This is because lateral erosion, through meander migration (so mainly hydraulic action and abrasion), has had time to occur

I hope this is helpful and in enough detail. It is quite a tricky area of the rivers model, especially if you are faced with a 15 mark question like 'Describe and explain the formation of landforms resulting from rejuvenation' as it is hard to think of enough to write about but hopefully this will give you an idea on where to start.

We are actually doing AQA (I think!) but I am guessing there is quite a bit of overlap between different exam boards. At AS we study Rivers, Population, Engery and Coasts and then at A2 Development and Globalisation, Plate Tectonics and Associated Hazards and Climate and Associated Hazards, with skills exams in both years - hopefully therefore some of this may still be relevant to the OCR course. There is also stuff on here about other modules we don't study within our syllabus like glaciers etc.

My teachers blog is called 'What I Taught in Geography This Week' and there is a link to it at the bottom of this blog, under Blogs I Read.

Geography Films

My Geography teacher is always reminding my class that watching (geography related) films can contribute to the 3 hours of reading time we are supposed to do each week. On both her blog and the Facebook page there are lists of recommended films and so I thought I would start to watch some of them and write a review on them from a student's perspective. If I would recommeded them to a fellow student then I will add the film to my own list below.......

- THE AGE OF STUPID (great film to watch for the energy module as it talks about climate change, energy consumption and production via some interesting case studies)

- THE COVE (this film is very thought provoking and presented the issues surrounding the dolphin trade - before watching this I didn't know a lot about the issue, especially the scale of it in Japan, and it left me feeling very shocked that something like this still exists today in such a developed country)

-ENCOUNTERS AT THE END OF THE WORLD (a great documentary with some simply stunning footage and interesting interviews that collectively provide an insight into life in Antarctica and the important research that is taking place)

-THE CONSTANT GARDENER (a rather sad story about how a drug company exploit the Kenyan population to allow them to test a new drug, despite the fact they know it has harmful side effects - good film for development and globalisation)

- ERIN BROCKOVICH (a good film that presents the negative impacts of the natural gas industry and the extent to which large companies are prepared to go to, to cover this up)

- SLUMDOG MILLIONAIRE (provides an insight into the life of children living in the Indian slums - good film to watch for development)

- GANDHI (a biopic about the life of Gandhi with particular reference to his prominent role in India's struggle for freedom from colonial rule)

- CRY FREEDOM (set in South Africa and tells the true story of Biko and his friendship with a white liberal newspaper editor - good film to watch for development)

- THE PAINTED VEIL (set in China, in the 1920's, and explores the impact of a cholera outbreak on a village, including references as to how religious beliefs make containing cholera even more challenging)

- BLOOD DIAMOND (set amid the explosive civil war overtaking 1999 Sierra Leone; it explores many issues including those surrounding the diamond trade, supply of arms to rebels and child soldiers - good film to watch for development and globalisation module)- THE DAY AFTER TOMORROW (after the Larsen B ice shelf collapses, the thermohaline circulation shutdowns, provoking glacial inception in the northern hemisphere - a good film to watch and then point out the geographical/scientific mistakes!)

- GOODBYE BAFANA (follows the unlikely friendship that forms between Mandela and his prision officer - good for development and globalisation)

- INVICTUS (after 27 years imprisionment, Mandela becomes South Africa's first elected president and this film follows his bid to unite the country via the rugby world cup - good film for development and globalisation)

- DARFUR (a group of international journalists travel to a village in Darfur in search of evidence to persuade the UN that genocide has occured but are forced to live after the Janjaweed turn up and threaten to kill them.... a film to watch for either development and globalisation or the population module but be warned it is very graphic)

Geography Books

I am a bit of a bookworm and often prefer reading a good book to watching a film and so (like I am doing with the Geography films) I am going to read some of the suggested books and write a review on them so I can comment on whether or not I think they are worth reading........

- AN INCONVENIENT TRUTH, Al Gore ( presents the issue of climate change and discusses how it has been caused and the impacts it is likely to have - well worth reading but if you prefer the film version is equally as a good)

- OUR CHOICE, Al Gore (this books follows on from An Inconvenient Truth by offering the solutions Al Gore thinks are required to solve the issue of Global Climate Change)

- THE BOY WHO HARNESSED THE WIND, William Kamkwamba and Bryan Mealer (tells the extraordinary true story of a Malawian teenager who overcame many obstacles to provide electricity and clean water for his village by capturing the energy in both the wind and the sun)

- BLOOD RIVER, Tim Butcher (tells the story of Tim Butchers quest to retrace the journey taken by H.M.Stanley in the 1870's. From this you get an insight into the history of the Congo and the factors that have effected its development - great book for the development and globalisation module as it provides an insight into the impact colonialism has had on Africa)

- GAIA, James Lovelock (presents the Gaia hypothesis which is the idea that the Earth functions as a living organism and so self-regulates to adapt to changing conditions - puts forward some very interesting ideas and really makes you think - it is worth a read!)

- THE REVENGE OF GAIA, James Lovelock (applies the Gaia hypothesis to global climate change - again an intriguing read which presents some interesting ideas and solutions to problems we are likely to face)

About Me

Whilst studying A-levels in Geography, Chemistry, Biology, Maths and History, I became completely fascinated by the Earth Sciences and found them particularly good for feeding my natural curiosity, providing answers to my never ending list of questions! Despite my relentless enthusiasm and frequent question asking, I was quite a quiet student in comparison to the rest of my class so my teacher asked me to start this blog as part of her experiment to test the benefits of incorporating social media into education. The aim was to find out if social networking can be a valuable educational tool and discover how much I actually learnt in lessons. It proved to be a huge success, for both myself and other students, with all my A-level notes still available for students use. I am currently at University studying BSc (Joint Honours) ‘Physical Geography with Oceanography’ and still asking way too many questions! In an attempt to continue to share my love for anything Earth Science-related, and to see if it can have the same benefits at Higher Education, I am trying to continue the blogging and use of social networking. I hope it proves to be a useful and interesting read!

The what, why and how of this blog.......

Hopefully you will have worked this out by now, but this blog is written from a student's perspective and, when combined with my teachers blog, should provide an insight into what I get taught - therefore what I should have learnt - in my Geography lessons. The idea is that this will make it a useful place to go to consolidate your learning; somewhere to go if you didn't quite understand something or missed a lesson. As well as this, posts will be written on anything of general geographical interest whether that be something currently in the news, anything related that I read or watch, anything I do or a topic that I just fancy finding out more about - all of this is designed to broaden our geographical knowledge. When it comes to revision I will try and write up as many notes as possible but it is unlikely that I will be able to cover everything so just let me know if there is anything you would like me to cover. So, thats what the blog is about (simply sharing, with anyone willing to read it, lots of geographical stuff that interests me!) and I am writing it because I tend to get a little enthusiastic about Geography and ask too many questions and so by channeling my interest in this way it will hopefully help you as much as it helps me!!! Whats the best way to use it? Well for starts reading/following the blogs and other resources is the only way you will benefit from them! Secondly, participate and get involved - comment on things, I am bound to get things wrong so correct me, you won't agree with everything I say so tell me what you think and perhaps even suggest things for me to read, watch or look into as I am always looking for new ways to extend my knowledge outside of the classroom. Geography is a discursive subject and, especially with human Geography, for the most part about forming/expressing opinions, so discuss the topics raised via the blogs etc. - trust me, its an easy way to learn!

I am now at University studying BSc (Joint Honours) Physical Geography with Oceanography - to keep my A-level notes separate I have started a new blog for current news and what I am learning in University - anything relevant I will also post on this blog, but please feel free to ask questions or requests posts! I hope students are still finding this a useful resource!

Disclaimer

'What I learnt in Geography this week.....' was created by, with content written by Vicki The Geography Student as part of an experiment conducted by Millie The Geography Teacher.

All posts published are my personal views, apart from where stated otherwise, and not those of the college I attended, my University or associated partners